Rotary abrasive tools particularly designed for cleaning or finishing interior cylindrical surfaces such as engine cylinder walls are employed both in rebuilding of engines and in original engine manufacture. The walls of such cylinders are required to have special surface finishes to enable the proper retention and distribution of lubricating oils. In engine rebuilding, the cylinder walls must also be cleaned of any glaze or deposit which builds up on the cylinder or valve seat walls in addition to imparting the lubricating oil holding finish. Examples of special abrading tools for such purposes may be seen in U.S. Pat. Nos. 3,384,915 and 3,871,139.
Such abrasive hones or brushes employ a round enlarged spherical globule of abrasive material on the tip of flexible nylon bristles. As in a round filament brush the initial contact with the work is a point and the abrasive loaded element then wears back to a flat. If a flat sided filament can be properly positioned against the interior surface to be honed or finished it has been found that more work per unit time can be achieved while properly finishing or cleaning the interior of the cylinder and also edges such as valve ports. Also, more consistent part-to-part results can be achieved.